Methods allowing for visual inspection of coated components for erosion damage

ABSTRACT

Methods allowing for visual inspection of a coated component for erosion damage involving providing a component, and applying a plurality of layers of an erosion system to at least a portion of the component to produce the coated component where each layer of the erosion system comprises a different color that becomes visible as the layer is eroded.

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims priority to Provisional Application Ser. No.61/037,524, filed Mar. 18, 2008, which is herein incorporated byreference in its entirety.

TECHNICAL FIELD

Embodiments described herein generally relate to methods allowing forvisual inspection of a coated component for erosion damage. Moreparticularly, embodiments herein generally describe methods comprisingproviding a component having a plurality of layers of an erosion systemwherein each layer of the erosion system comprises a different colorthat becomes visible as the layer is eroded.

BACKGROUND OF THE INVENTION

In gas turbine engines, such as aircraft engines, air is drawn into thefront of the engine, compressed by a shaft-mounted compressor, and mixedwith fuel in a combustor. The mixture is then burned and the hot exhaustgases are passed through a turbine mounted on the same shaft. The flowof combustion gas expands through the turbine, which in turn spins theshaft and provides power to the compressor. The hot exhaust gases arefurther expanded through nozzles at the back of the engine, generatingpowerful thrust, which drives the aircraft forward.

In recent years composite materials have become increasingly popular foruse in a variety of aerospace applications because of their durabilityand relative lightweight. Because engines operate in a variety ofconditions, engine components often come into contact with foreignobjects, such as hailstones, ice, sand, and dirt. Over time, contactwith such foreign objects can damage and erode the surface of thecomposite engine components.

To help protect the composite components from exposure to such harshenvironments, the surface of the component is often coated withexternal, secondarily applied materials. By “secondarily applied” it ismeant that the composite component is cured prior to the application ofthe coating. These secondarily applied materials may include polymercoatings that are sprayed, painted, or otherwise bonded to the compositecomponent. Other secondarily applied materials may include metal foilsor sheets that are preformed and bonded to the composite component. Ingeneral, this approach can require considerable labor and expense forpreparation and processing, typically requiring sanding and/or primingof the cured composite component prior to the application of thecoating.

In addition, to ensure that the finished component satisfies dimensionalconstraints, each component must be inspected after the protectivecoating is applied. For example, non-destructive evaluation techniques,such as the use of a coordinate-measuring machine, a hand gauge, orultrasonic inspection, can be used to determine if defects are present.If it is determined that there is significant coating thicknessvariation, which there often is, the coating must be stripped andreapplied. Even if the dimensions are found to be accurate, additionallabor is often needed to ensure the desired bond integrity and surfacefinish are achieved.

When it is discovered that a coated surface needs to be repaired, thedepth of the eroded portion can be measured to determine the extent ofthe wear. If the depth of erosion is small, the surface may be locallysanded, prepped, and recoated by spraying or painting a new coating ontothe eroded surface. If the depth of erosion is large, entire sections ofthe composite component may be removed and replaced with patches ofmaterial attached using epoxy or other suitable matrix material.

Accordingly, there remains a need for methods allowing for visualinspection of coated components for erosion damage.

BRIEF DESCRIPTION OF THE INVENTION

Embodiments herein generally relate to methods allowing for visualinspection of a coated component for erosion damage comprising providinga component, and applying a plurality of layers of an erosion system toat least a portion of the component to produce the coated componentwherein each layer of the erosion system comprises a different colorthat becomes visible as the layer is eroded.

Embodiments herein also generally relate to methods allowing for visualinspection of a coated component for erosion damage comprising providinga component, and applying a plurality of layers of an erosion system toat least a portion of the component to produce the coated componentwherein the erosion system comprises a support having a color and thesupport of each layer of the erosion system comprises a different colorthat becomes visible as the layer is eroded.

Embodiments herein also generally relate to methods allowing for visualinspection of a coated turbine engine component for erosion damagecomprising providing a turbine engine component having a surface, andapplying a first layer of an erosion system to at least a portion of thesurface of the turbine engine component, and applying at least a secondlayer of an erosion system to the first layer of the erosion system toproduce the coated component wherein each of the first layer and thesecond layer of the erosion system comprises a different color thatbecomes visible as the layer is eroded.

These and other features, aspects and advantages will become evident tothose skilled in the art from the following disclosure.

BRIEF DESCRIPTION OF THE DRAWINGS

While the specification concludes with claims particularly pointing outand distinctly claiming the invention, it is believed that theembodiments set forth herein will be better understood from thefollowing description in conjunction with the accompanying figures, inwhich like reference numerals identify like elements.

FIG. 1 is a schematic perspective view of one embodiment of a componentin accordance with the description herein;

FIG. 2 is a schematic cross-sectional view of the component of FIG. 1taken at line A-A in accordance with the description herein;

FIG. 3 is a schematic view of a portion of one embodiment of an erosionsystem showing both the support and the toughened resin in accordancewith the description herein;

FIG. 4 is a schematic cross-sectional view of the component of FIG. 1having a plurality of layers of an erosion system applied thereto inaccordance with the description herein; and

FIG. 5 is a schematic cross-sectional view of one embodiment of a coatedcomponent in accordance with the description herein.

DETAILED DESCRIPTION OF THE INVENTION

Embodiments described herein generally relate to methods allowing forvisual inspection of a coated component for erosion damage. The erosionsystems, components comprising the same, and methods for making the samedescribed herein may generally include a component and at least onelayer of an erosion coating system. Also described are improved methodsof inspection for articles comprising the erosion coating system.

Referring to FIG. 1, as used herein, “component” 10 may be used to referto any suitable part, which in one embodiment may be a turbine enginepart having at least one surface 12 capable of being coated as describedherein. Component 10 may generally comprise a composite, or acombination of a composite and a metal, such as titanium or titaniumalloy. For purposes of illustration, component 10 will be shown anddiscussed as a guide vane comprising both a metal and a composite,though the embodiments herein should not be limited to such.

For example, in one embodiment, component 10 may comprise a compositemade from a material including organic or non-organic fibers, and aresin matrix. More particularly, as used herein, “material” can refer toany woven, braided, or non-crimp fabric or fibers capable of beingtreated and cured with a resin to produce a composite. In oneembodiment, the material may comprise carbon fibers, graphite fibers,glass fibers, ceramic fibers, aramid polymer fibers (e.g. Kevlar®), andcombinations thereof. As shown in FIG. 2 and as will be understood bythose skilled in the art, component 10 may comprise a plurality oflayers of a material 14, and that each of such layers may comprise thesame, or different, weaves, braids, and/or fiber composition. Ifcomponent 10 comprises a composite and a metal, material 14 can be laidup using conventional fabrication techniques to achieve the desiredshape such as wrapping the plurality of layers of material 14 about ametal spar 15 that will become part of the finished coated component.Resin infusion can be carried out at a later point in the process asdescribed herein below.

Component 10 may take any shape desired to carry out its intendedpurpose. By way of example, some acceptable turbine engine componentssuitable for use herein may include, but should not be limited to,vanes, blades, struts, ducts, spacers, and the like. Those skilled inthe art will understand that although the examples provided hereinrelate to turbine engines, “component” may be used to refer to any partmatching the previous description.

As shown in FIG. 3, an erosion system 16 can then be prepared for laterapplication to the component. As used herein, “erosion system” refers toa layered coating comprising a toughened resin 18 applied to a support20, as defined herein below.

Erosion system 16 can utilize a resin 22 to serve as a composite matrix.Resin 22 can comprise any conventional liquid resin known to thoseskilled in the art, such as, but not limited to, epoxy resin,bismaleimide resin, or polyimide resin. A toughening agent 24 can thenbe added to resin 22 to produce toughened resin 18 that can provideerosion resistance upon curing. Some examples of toughening agents 24can include, but should not be limited to, fibers, nano fibers, nanoparticulates, and combinations thereof. Some examples of possible fiberscan include carbon fibers, graphite fibers, glass fibers, ceramicfibers, aramid polymer fibers, and combinations thereof. While theamount of toughening agent 24 added to resin 22 can vary depending onthe final toughness desired after curing, in general, toughened resin 18can comprise from about 0.1% to about 25%, by weight, of tougheningagent 24.

As shown in FIG. 3, toughened resin 18 may be applied to support 20. Asused herein, “support” refers to any mesh, netting, webbing, or othersuitable structure to which toughened resin 18 can be applied. Support20 can comprise, but should not be limited to, carbon fibers, graphitefibers, glass fibers, ceramic fibers, aramid polymer fibers, andcombinations thereof. Those skilled in the art will understand thatwhile the dimensions of support 20 can vary, the fibers of the supportshould be capable of retaining the applied toughened resin 18. Erosionsystem 16 can then be applied to at least a portion of surface 12 ofcomponent 10 by wrapping, for example, as shown in FIG. 4. The tackinessof the toughened resin present in the erosion system can help secureerosion system 16 in place for further processing.

For ease of transfer and handling, in one embodiment, erosion system 16can be applied with the aid of a backing 26 on the side opposed to thecomponent, as shown in FIG. 4. Once the layer of erosion system 16 isapplied, backing 26 can be peeled away. This process can be repeated forthe application of additional layers of erosion system 16 if desired.

Moreover, if a plurality of layers of erosion system 16 is desired, inone embodiment, each layer may comprise the same combination of thetoughened resin and the support. Alternately, in another embodiment,each layer can comprise a support having a different color. The coloredlayers can be stacked to reveal different depths of penetration aserosion occurs. For example, if the erosion system has three layers, afirst layer 28, a second layer 30, and a third layer 32, first layer 28can comprise support 20 that is blue in color, second layer 30 cancomprise support 20 that is yellow in color, and third layer 32 cancomprise support 20 that is green in color. These colors can serve andas indicator of the degree of erosion present on a component. The colorsof the support can be achieved by a variety of methods, including, butnot limited to, constructing the support from fibers of differentcolors.

Once the desired layers of erosion system 16 have been applied,component 10 comprising erosion system 16 can be co-molded usingconventional techniques known to those skilled in the art, for example,compression molding, resin transfer molding, vacuum assisted resintransfer molding, or autoclaving. As used herein, “co-molding” refers toinfusing resin into both the component and the layers of the erosionsystem concurrently. Component 10 comprising erosion system 16 can becured concurrently using standard curing conditions known to thoseskilled in the art. The result is a coated component 34 wherein erosionsystem 16 remains as a composite film at the outermost layer, therebyproviding coated component 34 with protection from the elements, asshown generally in FIG. 5. Those skilled in the art will understand thatthe previously described methods for making an applying the erosionsystem are equally applicable if the component comprises a metal, or acombination of a composite and metal.

The previously described coating system offers several benefits overcurrent coatings including superior erosion protection, visualidentification of the coated component for maintenance issues, and theability to co-mold.

The erosion system described herein can provide from about a 50%increase to about a 400% increase in erosion resistance to theunderlying component per layer of the erosion system utilized whencompared to conventional erosion protection mechanisms. This increase inerosion resistance can be measured as the mass loss of coatingcorresponding to a given flux of abrasive material, such as sand. Oncecured, the incorporation of the previously described toughening agentsinto the liquid resin can allow the erosion system to serve as anintegral barrier between the outside elements and the coated composite.Without intending to be limited by theory, the addition of the fibers tothe resin makes the toughened resin a composite film after curing. Thiscomposite film is better able to withstand erosion attributable toelemental exposure.

Moreover the inclusion of a plurality of layers of the erosion system,each having a different colored support, can provide for visualidentification of erosion. As the erosion system erodes from exposure tothe elements, different colored layers of the support are revealed. Byvisually inspecting the colors of the exposed mesh, it can be determinedhow deep into the erosion system the erosion has penetrated. This visualinspection can increase the efficiency of making assessments of theintegrity of the erosion system for purposes of maintenance or repair,as compared to conventional techniques.

In addition, the ability to co-mold the present embodiments can providenet shaped coated components displaying more dimensional consistency andless variation between coated components. In this way, the sanding,priming, and painting steps generally required by conventionalmanufacturing can be substantially eliminated. Co-molding can also helpreduce the cost and time involved in manufacturing such coatedcomponents. In addition, a variety of erosion resistance improvementscan be achieved in a single component by applying a different number oflayers of material to the component, by selectively positioning theplacement of the material about the component, or a combination thereof.Moreover, the ability to selectively improve erosion in specificportions of the component can further help save costs by eliminating theneed to coat the entire component.

This written description uses examples to disclose the invention,including the best mode, and also to enable any person skilled in theart to make and use the invention. The patentable scope of the inventionis defined by the claims, and may include other examples that occur tothose skilled in the art. Such other examples are intended to be withinthe scope of the claims if they have structural elements that do notdiffer from the literal language of the claims, or if they includeequivalent structural elements with insubstantial differences from theliteral language of the claims.

1. A method allowing for visual inspection of a coated component forerosion damage comprising: providing a metal component; and wrapping aplurality of layers of an erosion system to at least a portion of thecomponent to produce the coated component, each layer of the erosionsystem comprising: a toughened resin applied to a support wherein themetal comprises titanium, a titanium alloy, or a combination thereof andwherein the support of each layer of the erosion system comprises adifferent color that becomes visible as the layer is eroded.
 2. Themethod of claim 1 wherein the erosion system comprises a support havinga color and the support of each layer of the erosion system comprises adifferent color.
 3. The method of claim 2 wherein the support comprisesa structure selected from the group consisting of mesh, netting,webbing, and combinations thereof.
 4. The method of claim 2 wherein thesupport is comprises fibers selected from the group consisting of carbonfibers, graphite fibers, glass fibers, ceramic fibers, aramid polymerfibers, and combinations thereof.
 5. The method of claim 1 comprisingwrapping the plurality of layers of the erosion system to a turbineengine component selected from the group consisting of vanes, blades,struts, ducts, and spacers.
 6. A method allowing for visual inspectionof a coated component for erosion damage comprising: providing a metalcomponent; and wrapping a plurality of layers of an erosion system to atleast a portion of the component to produce the coated component, eachlayer of the erosion system comprises: a resin selected from the groupconsisting of epoxy, bismaleimide, polyimide, and combinations thereof,combined with; a toughening agent selected from the group consisting ofcarbon fibers, graphite fibers, glass fibers, ceramic fibers, aramidpolymer fibers, and combinations thereof, to produce a toughened resinthat is applied to a support wherein the metal comprises titanium, atitanium alloy, or a combination thereof and wherein the support of eachlayer of the erosion system comprises a different color that becomesvisible as the layer is eroded.
 7. The method of claim 6 wherein thesupport comprises a structure selected from the group consisting ofmesh, netting, webbing, and combinations thereof.
 8. The method of claim7 wherein the support is comprises fibers selected from the groupconsisting of carbon fibers, graphite fibers, glass fibers, ceramicfibers, aramid polymer fibers, and combinations thereof.
 9. The methodof claim 8 comprising wrapping the plurality of layers of the erosionsystem to a turbine engine component selected from the group consistingof vanes, blades, struts, ducts, and spacers.
 10. A method allowing forvisual inspection of a coated turbine engine component for erosiondamage comprising: providing a metal turbine engine component having asurface; wrapping a first layer of an erosion system to at least aportion of the surface of the turbine engine component; and wrapping atleast a second layer of an erosion system to the first layer of theerosion system to produce the coated component wherein the metalcomprises titanium, a titanium alloy, or a combination thereof andwherein each of the first layer and the second layer of the erosionsystem comprises a toughened resin applied to a support of a differentcolor that becomes visible as the layer is eroded.
 11. The method ofclaim 10 comprising wrapping the plurality of layers of the erosionsystem to a turbine engine component selected from the group consistingof vanes, blades, struts, ducts, and spacers.